Mold closing device with mold height adjustment and method for actuation thereof

ABSTRACT

A mold height adjustment device for modifying the distance between the stationary mold carrier and a support element by means of a drive mechanism is provided in a plastic injection molding machining. A locking device locks the support element in its respective position. A release position is provided in the area of movement of the moving mold carrier, which unlocks the locking device when the moving mold carrier is in the release position, thereby providing a mold height adjustment device and a method for actuating the device, which advantageously uses the elements moving on the machine for its actuation.

REFERENCE TO RELATED APPLICATIONS

The present invention claims the priority of German patent application102 10 869.2, filed on Dec. 3, 2002, the disclosure content of which ishereby expressly also made the object of the present application.

FIELD OF THE INVENTION

The invention relates to a mold closing unit for an injection moldingmachine for processing plastics materials and other plasticizablesubstances having a mold height adjustment according to the mainpreamble of claim 1 as well as to a method for actuating this type ofmold height adjustment according to the main preamble of claim 11.

STATE OF THE ART

This type of mold height adjusting means is known in DE 198 12 741 A1 tothe extent that the mold closing unit can adjust the position of thesupporting element in its own closing device. To this end, a lockingdevice is provided respectively on the movable mold carrier and also onthe supporting element for the closing device. In the standard conditionfor the production process, the supporting element is locked and themovable mold carrier is released for displacement, that-is-to-say isunlocked. If the height of the mold has to be changed, the movable moldcarrier is locked and the supporting element released, such that whenthe closing device is activated, the position of the supporting elementcan be altered. This type of apparatus, however, from a certain size ofmachine, is no longer suitable for displacing the supporting elementuniformly without canting.

U.S. Pat. No. 4,281,977 A makes known a mold height adjusting means,where, threaded portions, which are connected to nuts, are provided oncolumns, which are mostly secured to the stationary mold carrier andserve as a guiding means for the movable mold carrier. These nuts aredriven via a separate driving means for adjusting the height of themold. On the outside of these nuts there is an annular gear, which meansthat they can be actuated either by means of an annular gear or by meansof a toothed belt.

For adjusting the height of the mold and locking a supporting plate forthe closing mechanism, it is known from Engel Vertriebs GmbH, A-4311Schwertberg, Austria, 1996, to provide columns with grooves and to clampsecuredly two half-nuts to these grooves by moving the half-nuts towardsone another in the radial direction until they abut against the groovedregion of the guide columns.

Husky Injection Molding Systems, Moduline E-Series Machines, September1996, made known this type of locking means with a bayonet closure. Thecolumn, for this purpose, has regions in which a closing piston canengage, as well as regions along which the closing piston, which isdisplaceable radially on the guide columns, can slide. Rotating thisclosing piston effects a positive engagement, which means that, at thesame time, at least a portion of the closing force can also be appliedto this piston.

SUMMARY OF THE INVENTION

Proceeding from this state of the art, it is the object of the presentinvention to provide a mold height adjustment for a mold closing unitand a method for actuating the mold height adjustment, which mold heightadjustment uses in an advantageous manner for its actuation the movingparts which are present in any case on the machine.

This object is achieved by a mold closing unit with the features ofclaim 1 and by a method with the features of claim 11.

The mold closing unit and the method are configured in such a mannerthat a release position is provided for the movable mold carrierinternally of its displacement region, in which release position themold carrier, as soon as it is transferred into this position, canactuate the locking device, that-is-to-say can unlock it. This leads toa relatively simple unlocking procedure as the mold carrier only has tobe transferred into this region again and can subsequently adjust thesupporting element. If the movable mold carrier is not situated in thisregion, the supporting element is automatically locked. Therefore,additional costly sensors or transferring mechanisms do not have to beprovided. The construction of the locking device can be arbitrary if itis ensured that the movable mold carrier, as soon as it is in therelease position, effects the unlocking of the locking device of thesupporting element.

Further details are produced from the subclaims.

SHORT DESCRIPTION OF THE FIGURES

The invention is described in more detail below by way of an exemplifiedembodiment. In which:

FIG. 1 is a side view of a mold closing unit for an injection moldingmachine,

FIG. 2 is an enlarged cutout from FIG. 1 in the region of the lockingdevice,

FIG. 3 is a rear view of the injection molding machine in FIG. 1 fromthe left,

FIG. 4 is a view according to the lines 4-4 in FIG. 3 with a sectionthrough the locking device.

DETAILED DESCRIPTION OF PREFERRED EXEMPLIFIED EMBODIMENTS

The invention is now described in more detail below in an exemplarymanner with reference to the enclosed drawings. However, the exemplifiedembodiments are only examples, which are not meant to restrict theinventive concept to one specific arrangement.

FIG. 1 shows the side view of a mold closing unit for a plasticinjection molding machine, which can be used for processing plasticsmaterials and other plasticizable substances such as powdery or ceramicsubstances. The mold closing unit is disposed on the machine base 12 andincludes a stationary mold carrier 10 and a movable mold carrier 11.Injection molds 13 of variable height can be disposed between the moldcarriers in a mold clamping area R. The height of the mold overall isthe measurement that is produced from the sum of the measurements a₁ anda₂. The movable mold carrier 11 is constructed in the form of a frame,which includes, as shown in FIG. 1, the right-hand plate, to which theone half of the injection mold 13 is securable, and a rear plate, saidplates being interconnected via the cylinder of the closing device 20.This produces a box plate, which is actuated by the pistons (notrepresented in the drawing) of the closing device. These pistons aresupported conventionally on the supporting element 21. However,electromechanical drives or linear drives or other driving means canalso be provided in place of the described hydraulic or pneumatic pistoncylinder units in the form of the closing device 20.

In the exemplified embodiment, guide elements 17 are provided in theform of guide braces or guide columns, which are mounted on thestationary mold carrier 10. They serve, in the exemplified embodiment,both the movable mold carrier 11 and the supporting element 21 asguiding means for their movement, which has yet to be described. Inprinciple, the mold height adjustment described below can also be usedon an injection molding machine without braces, where the stationarymold carrier and the movable mold carrier are interconnected via a forcetransferring element, for example one or several brackets, guided aroundthe mold clamping area R. In this case, only one correspondingdisplacement region for the supporting element has to be made possible,this latter then having to be guided in a suitable manner, for example,at one end of the bracket.

Associated with the supporting element 21 is a mold height adjustment14, which serves for adjusting the distance x between the stationarymold carrier 10 and the supporting element 21 by moving the supportingelement. The closing device can be optimized by changing the moldheight. If, with a small injection mold 13, the supporting element inFIG. 1 is displaced to the right, the cycle times are initially reduced,as the movable mold carrier does not have to open the mold to the sameextent as, for example, represented in FIG. 1. However, the path of theclosing device can also be optimized by the adjustment, that-is-to-say,for example, can be minimized in the case of a small injection mold,which means that the pressure build-up times can be drastically reduced.The advantage this produces can contribute to a reduction in cycle timesof several 1/10 seconds.

In order to enable an automatic mold height adjustment, a drive 15 isprovided, which can be seen best in FIG. 3. The drive 15 actuates, viachangeover mechanisms (not represented in the drawings), variousspindles 15 a, which in their turn, are in engagement with the moldheight adjustment 14 associated with each column 17. As soon as the moldheight adjustment is unlocked by transferring the movable mold carrier11 into the release position, the mold height adjustment can be actuatedvia the drive 15 and the spindles 15 a at each of the guide elements 17at the same time.

In order to ensure that the supporting element is reliably retained atthe columns, when the not inconsiderable forces of the closing device 20are applied during the injection molding cycle, a locking device 16 isprovided for locking the supporting element 21 in its respectiveposition. The effect and actuation of the locking device is described inmore detail below by way of FIGS. 2 and 4.

For actuating the locking device, there is provided a release positionin the displacement region of the movable mold carrier 11, which releaseposition effects the unlocking of the locking device 16 when the movablemold carrier 11 is in the release position. In principle, therefore,there is no need for any additional sensors, the transferring of themovable mold carrier into the release position simply ensures that thelocking device is unlocked, such that subsequently the drive 15 of themold height adjustment 14 can adjust the supporting element 21 bychanging the distance x. This release position is provided externallyand at the end, which is remote from the stationary mold carrier 10, ofthe displacement region of the movable mold carrier 11, whichdisplacement region is necessary during the actual injection moldingprocess. If, therefore, after conclusion of the production of a certaininjection molding, a mold height adjustment is to be executed, themovable mold carrier “overtravels” the previously admitted displacementregion and is brought into the release position. In this releaseposition are provided auxiliary means that make sure that the lockingdevice 16 can be unlocked. In this case, the unlocking procedure mustnot be carried out as below; instead of the bolts 26 yet to be describedand the resilient means 18, lever mechanisms or similar can also beprovided, which are only to ensure that the existing locking isreleased. The mold height adjustment 14 itself is disposed on thesupporting element 21. As shown in FIGS. 2 and 4, it includes nuts,which engage with threaded portions 17 a on the guide elements 17 forthe supporting element 21. If the drive 15 is actuated, these nuts aredriven via the spindles 15 a.

In the exemplified embodiment, there are preferably provided on eachguide element at least two nuts 22, 23, which are clamped as aconsequence of the effect of the resilient means 18 of the lockingdevice 16. The nuts 22, 23 abut against the clamping sleeve 25 on oneside and against the supporting element 21 on the other side, both beingin operative connection with one another by means of connecting means 26mounted thereon and clamping the nuts 22, 23 under the effect of theresilient means 18. In place of the counter nut solution given in thiscase, just one nut can also work as long as the nut is securedcorrespondingly in its respective position in another manner. However,the advantage of the following solution is that the effect of the nutsand the effect of the locking device, although they work in the directvicinity of one another, are separate from one another. The clampingeffect, in this regard, is provided, for example, by resilient means,which the movable mold carrier makes inoperative in the releaseposition. Consequently, it is not necessary to release the clampingmanually in order subsequently to be able to move the supportingelement, but rather the adjustability of the supporting element isprovided as soon as the effect of the resilient means is lifted by themovable mold carrier.

The connecting means 26 are bolts, which penetrate a bore 21 a of thesupporting element. Spring washers in the form of resilient means 18 aremounted between bolts and clamping sleeve 25 or—as in the exemplifiedembodiment—supporting element 21. FIG. 4 shows that the bolt 26 issecured to the clamping sleeve 25 with a screw 26 a and abuts againstthe supporting element 21 by means of the resilient means 18. This isachieved in that the bolt, at the end remote from its head 26 a, has aregion 26 b with a larger diameter, which serves the resilient means 18as a bearing arrangement. Other suitable resilient means can be providedin place of the spring washers, as long as they are actuatable by meansof the transferring of the movable mold carrier into its releaseposition.

The connecting means 26, that-is-to-say the bolts, project in thedirection of the movable mold carrier as far as into the region of therelease position. The movable mold carrier 11, in its turn, has anactuating face 11 a, which, in the release position of the movable moldcarrier, actuates the connecting means 26 by lifting the locking effectof the resilient means 18. If, therefore, the movable mold carrier inFIG. 4 is moved further to the left, the actuating face 11 a comes toabut against the bolt. If the movable mold carrier is moved even furtherto the left, the bolt is pressed to the left in opposition to the forceof the resilient means 18, which means that the clamping effect betweenthe nuts 22 and 23 is lifted. The nuts are clamped in a known manner bymeans of radial locking pins, the effect of which is also lifted whenthe effect of the resilient means 18 is lifted. It is then possible forthe drive 15 to adjust the nuts. The actuating face 11 a is disposed inthe region of a bore of the movable mold carrier, which bore is passedthrough by the guide elements 17 which are in the form of guide columns.

As soon as the movable mold carrier 11 actuates the resilient means 18,the movable mold carrier abuts against the resilient means 18 with alarge part of its surface area. As this abutting is effected through amovement along the guide elements 17, the force consequently isintroduced in a substantially linear manner onto the resilient means 18and the nuts 22, 23. At the same time, there is a closed force flowbetween the movable mold carrier 11 and the supporting element 21. Thismeans that the forces are applied in a torque-free manner, which meansthat there is no canting when the supporting element 21 is adjusted. Theadjusting is effected in an almost friction-free manner. Furtheradditional auxiliary means are not necessary.

In principle, it must be ensured that the movable mold carrier remainsin its conventional displacement region during the production processand does not pass into the release position. To this end, the clampingbolts, which are present in any case, are guided through the supportingelement, which means that they project as far as into the region of therelease position. If the movable mold carrier is then transferred intothis region, the desired solution is produced.

The following steps are necessary for adjusting the mold height:

-   -   Releasing the supporting element 21 from its position, which was        coordinated with the previous mold height, by opening the        locking device 16,    -   Changing the distance x between the stationary mold carrier and        the supporting element 21 by moving the supporting element 21 by        means of the drive 15,    -   Securing the supporting element 21 in the amended position,        which is coordinated with the new mold height, by locking the        locking device 16.

The releasing of the supporting element 21 is effected by the movablemold carrier 11 being transferred into the release position. Thetransferring into the release position effects the unlocking of thelocking device 16. The movable mold carrier 11 is preferably transferredinto this position by means of its own closing device 20, which meansthat no means other than the closing device, which is present in anycase, are necessary for this purpose. Whilst the distance x is beingchanged, the supporting element 21 and the movable mold carrier 11 aremoved together. There should therefore be coordination between theeffect of the closing device 20 and the drive 15.

To change the distance x or respectively the mold height, the drive 15actuates the nuts 22, 23 and adjusts them along the threaded portions 17a of the guide elements 17. However, this is not possible until thenuts, which have been checked in principle by the effect of theresilient means 18 of the locking device 16, are un-checked. The movablemold carrier 11, therefore, brings the connecting means 26, inopposition to the force of the resilient means 18, into a position,which enables a lifting of the checking effect.

It is obvious that this description can be subject to the most variedmodifications, changes and adaptations, which are considered asequivalent to the enclosed claims.

List of References

-   -   10 Stationary mold carrier    -   11 Movable mold carrier    -   11 a Actuating face    -   12 Machine base    -   13 Injection mold    -   14 Mold height adjustment    -   15 Drive for 14    -   15 a Spindle    -   16 Locking device    -   17 Guide element    -   17 a Threaded portion    -   18 Resilient means    -   20 Closing device    -   21 Supporting element    -   21 a Bore    -   22, 23 Nut    -   25 Clamping sleeve    -   26 Bolt    -   26 a Screw    -   26 b Region with a larger diameter    -   a Mold height    -   s-s Closing device    -   x Distance between 10 and 21    -   R Mold clamping area

1-17. (canceled)
 18. Mold closing unit having an apparatus forautomatically adapting to the mold height of injection molds of variableheight measured in closing direction for an injection molding machinefor processing plastics materials and other plasticizable substances,the mold closing unit comprising: a stationary mold carrier; a movablemold carrier; a closing device for moving the movable mold carrier inthe closing direction towards the stationary mold carrier and away fromthe stationary mold carrier; an injection mold of variable heightmeasured in the closing direction, said injection mold beingaccomodatable in a distance between the stationary mold carrier and themovable mold carrier; a supporting element for the closing device; amold height adjustment for adjusting the distance between stationarymold carrier and supporting element by moving the supporting element; adrive for automatically adjusting the mold height adjustment; a lockingdevice for locking the supporting element in its respective position,wherein a release position is provided in the displacement region of themovable mold carrier, the release position effecting the unlocking ofthe locking device when the movable mold carrier is in the releaseposition.
 19. Mold closing unit according to claim 18, wherein therelease position is externally of and at the end, which is remote fromthe stationary mold carrier, of an injection displacement region of themovable mold carrier, which injection displacement region is requiredfor an injection molding process.
 20. Mold closing unit according toclaim 18, wherein the mold height adjustment is disposed on thesupporting element.
 21. Mold closing unit according to claim 18, whereinthe mold height adjustment includes nuts, which engage by means ofthreaded portions on guiding elements for the supporting element and areadjustable by means of the drive.
 22. Mold closing unit according toclaim 21, wherein at least two nuts in each case are clamped as a resultof the effect of resilient means of the locking device.
 23. Mold closingunit according to claim 21, wherein the nuts abut against a clampingsleeve and the supporting element, both of which are in operativeconnection through connecting means mounted thereon and clamp the nutsunder the effect of resilient means.
 24. Mold closing unit according toclaim 23, wherein the connecting means are bolts which penetrate atleast the supporting element, and in that spring washers are provided asthe resilient means and are mounted between the bolts and a clampingsleeve and/or the supporting element.
 25. Mold closing unit according toclaim 24, wherein the bolts are secured with a screw to the clampingsleeve and are mounted on the supporting element by means of theresilient means.
 26. Mold closing unit according to claim 18, wherein atleast one unlocker is mounted on the supporting element and projects inthe direction of the movable mold carrier as far as into the region ofthe release position, and wherein the movable mold carrier includes anactuating face, which, in the release position of the movable moldcarrier, actuates the unlocker by lifting the locking effect of aresilient means.
 27. Mold closing unit according to claim 26, whereinthe unlocker is a connecting means operatively connecting a clampingsleeve and the supporting element.
 28. Mold closing unit according toclaim 26, wherein the actuating face is disposed in the region of aguiding bore for guiding the movable mold carrier along the guideelements.
 29. Method for automatically adapting the mold height ofinjection molds of variable height measured in closing direction on aninjection molding machine for processing plastics materials and otherplasticizable materials, the mold closing unit having: a stationary moldcarrier, a movable mold carrier, a supporting element for a closingdevice for moving the movable mold carrier towards the stationary moldcarrier and away from the stationary mold carrier, a mold heightadjustment, a drive for adjusting the mold height, a locking device forlocking the supporting element in its respective position, the methodcomprising: releasing the supporting element from a position coordinatedwith a first mold height by opening the locking device; changing adistance between the stationary mold carrier and the supporting elementby moving the supporting element by means of the drive; and securing thesupporting element in a second position, coordinated with a new moldheight by locking the locking device, wherein the movable mold carrier,in a release position for releasing the supporting element, unlocks thelocking device.
 30. Method according to claim 29, wherein the movablemold carrier is transferred by the closing device into a position foractuating the locking device.
 31. Method according to claim 30, whereinthe position for actuating the locking device is at an end remote fromthe stationary mold carrier of an injection displacement region of themovable mold carrier required for an injection molding process. 32.Method according to claim 29, wherein during the changing of thedistance, supporting element and movable mold carrier are movedtogether.
 33. Method according to claim 29, wherein, for changing thedistance, the drive actuates nuts and adjusts them along threadedportions, which, in the secured condition, are checked by the lockingdevice.
 34. Method according to claims 33, wherein when the movable moldcarrier approaches the supporting element, it releases resilient meansand lifts the checking effect between the nuts.
 35. Method according toclaims 34, wherein, through the movement of the movable mold carrierinto the release position along guide elements, the force for liftingthe effect of resilient means is introduced to the resilient means in asubstantially linear manner.